The Triumph GT6 Gearbox


The all-synchromesh gearbox, although making use of several well-proved Vitesse components, was a new design. The aluminium alloy bellhousing is a separate casing to the cast iron gearbox casing, a new design developed to accommodate the re-arranged gears and synchromesh mechanism on bottom gear. Attached to the rear is the extension which houses the tail end of the mainshaft. On the Spitfire and Vitesse gearboxes, first gear and reverse are engaged by sliding the non-synchronized mainshaft gear into mesh with the appropriate train. On the GT6 the first gear is in constant mesh, but free to rotate on the mainshaft to which it is connected by the dog-teeth of the synchromesh mechanism. Reverse is engaged by sliding the reverse idler idler into line with the reverse gears on the layshaft and mainshaft; the mainshaft gear is part of the synchromesh assembly for 1st and 2nd gears. Synchromesh is of the constant-load type common to all Triumph models except the 1300; it should inherit the robust effectiveness of the previous designs. Ratios are very close, with bottom gear high at 8.66 to 1. The car is reputed to reach 46 mph in bottom, 68 mph in 2nd, and no less than 96 mph in third. This gearbox was first developed on prototype competition Spitfires during 1964 and 1965.

The above is from the Autocar article published in Turning Circle APRIL 1983 No.4.

GT6 Mk2